Spatio-temporal querying in video databases

A video data model that supports spatio-temporal querying in videos is presented. The data model is focused on the semantic content of video streams. Objects, events, activities, and spatial properties of objects are main interests of the model. The data model enables the user to query fuzzy spatio-temporal relationships between video objects and also trajectories of moving objects. A prototype of the proposed model has been implemented.     

Characterization of Fines Produced by Sand Crushing

Sand particle crushing generates coarse fragments with size d ≥ 75?μm and fine fragments, i.e., “fines,” with size d<75?μm. Yet, postcrushing fines are seldom characterized due to testing constraints. An experimental study was conducted to examine the size distribution evolution of fine fragments generated by crushing two uniform sands with contrasting degrees of mineral composition heterogeneity, in one-dimensional compression. The determination of fine fragment sizes was made possible by using a particle size analyzer that employs a small sample. The results indicate that the degree of mineral composition heterogeneity affects the load–deformation behavior of crushing sands and the resulting amounts and size distribution evolutions of the produced coarse and fine fragments. In particular, the trends gathered suggest that fines generation occurs by abrasion of parent particles, coarse fragment breakage, and subsequent breakage of fine fragments with sizes larger than the comminution limit.